2008/02/25 by Prasad Subramanian, Peter A. Becker, Menas Kafatos +1
Physics and Astronomy · #Accretion (finance) #Accretion disc #Advection #Angular momentum #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Classical mechanics #Instability #Magnetic field #Magnetohydrodynamics #Magnetorotational instability #Mechanics #Nuclear physics #Physics #Plasma #Stellar, planetary, and galactic studies #Thermodynamics #Viscosity #Viscous stress tensor #astro-ph
paper · pdf · doi:10.1007/978-1-4020-8868-1_16
To appear in the proceedings of the first Kodai-Trieste workshop on Plasma Astrophysics (Aug 27-Sept 07 2007), Springer Astrophysics and Space Science Proceedings series
arxiv created 2008/02/25 · openalex publication_date 2008/10/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We aim to illustrate the role of hot protons in enhancing the magnetorotational instability (MRI) via the ``hybrid'' viscosity, which is due to the redirection of protons interacting with static magnetic field perturbations, and to establish that it is the only relevant mechanism in this situation. It has recently been shown by Balbus \citePBM1 and Islam & Balbus \citePBM11 using a fluid approach that viscous momentum transport is key to the development of the MRI in accretion disks for a wide range of parameters. However, their results do not apply in hot, advection-dominated disks, which are collisionless. We develop a fluid picture using the hybrid viscosity mechanism, that applies in the collisionless limit. We demonstrate that viscous effects arising from this mechanism can significantly enhance the growth of the MRI as long as the plasma β\gapprox 80. Our results facilitate for the first time a direct comparison between the MHD and quasi-kinetic treatments of the magnetoviscous instability in hot, collisionless disks.